Various systems directed to fusion of the spine have been proposed. Examples include the systems described in the following U.S. Patents issued to Gary Michelson: U.S. Pat. No. 6,527,776, entitled “Locking Element For Locking At Least Two Bone Screws To An Orthopedic Device”; U.S. Pat. No. 6,592,586, entitled “Single-Lock Anterior Cervical Plating System”; U.S. Pat. No. 6,428,542, entitled “Single-Lock Anterior Cervical Plate System”; U.S. Pat. No. 6,398,783, entitled “Multi-Lock Anterior Cervical Plate”; U.S. Pat. No. 6,383,186, entitled “Single-Lock Skeletal Plating System”; and U.S. Pat. No. 6,193,721, entitled “Multi-Lock Anterior Cervical Plating System”.
Of note, each of the above patents appears to disclose a system in which one or more bone screws are held to the bone plate via a locking mechanism (such as a screw) which rotates relative to the bone plate.
Likewise, U.S. Pat. No. 6,152,927, entitled “Anterior Cervical Plating System” and U.S. Pat. No. 6,669,700, entitled “Anterior Cervical Plating System” appear to disclose a system in which one or more bone screws are held to the bone plate via a locking mechanism (such as a screw) which rotates relative to the bone plate.
Finally, each of U.S. Pat. No. 6,224,602, entitled “Bone Stabilization Plate With A Secured-Locking Mechanism For Cervical Fixation” and U.S. Pat. No. 6,533,786, entitled “Anterior Cervical Plating System” appears to disclose a system in which one or more bone screws are held to the bone plate via a locking mechanism which slides relative to the bone plate.
Of note, however, in these last two aforementioned systems it appears that each of the locking mechanisms is provided with only one degree of freedom, such that the locking mechanism may slide relative to the bone plate but may not be moved up or down relative to the bone plate (and relative to the bone screws within the bone plate). Thus, these last two aforementioned systems do not appear capable of providing pressure on bone screws which are disposed at varying depths relative to the bone plate.
Among those benefits and improvements that have been disclosed, other objects and advantages of this invention will become apparent from the following description taken in conjunction with the accompanying figures. The figures constitute a part of this specification and include illustrative embodiments of the present invention and illustrate various objects and features thereof.